Apparently, the prevailing theory is a program to cyber-sabotage the launch systems[0].
[0]: https://www.nytimes.com/2017/03/04/world/asia/north-korea-mi...
[0]: https://www.nytimes.com/2017/03/04/world/asia/north-korea-mi...
Scuttling them at sea is nice and all --having them go up and straight back down would present the regime with quite a problem.